Process for making insulating-tubes.



v. P. 'VON PINDTERSHOFEN. PROCESS FOR MAKING INSULATING TUBES.

APPLICATION FILED OCT. 27, 1910.

Patented May 7, 1912.

a n newton UNITED sTA'rEs PATENT OFFICE.

VICTOR PIND'IER v. PINLDTERSHbFEN, OF WIENER-NEUSTADT,AUSTRIA-HUNGARY- FBOCESQ FOR MAKING INsUIATlNG TUBEs.

Application filed fletober 27, 1910. Serial No. 55937.

To (ill whom it may concern:

Be it 'known that I, VICTOR Pmn'rna VON PINDIERSHOFEN,'ClVll engineer, a subject of ,the'Emperor of Austria-Hungary, residing at Wiener-Neustadt, l iust-ria-l-lungary, have invented certain new and useful Improvements in Processes for Making Insulating- Tubes andI do hereby declare the follow ing to be atull, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertainslto make and use the same.

Insulating tubes have already been made of fibrous material or paper by coiling these materials on a mandrel. In the greater number of those processes the paper, etc., is impregnated with an insulating composition shortly before, or during the coiling operation, so that the insulating tube is ready for use. It has also been proposed to coil fibrous material in the form of a continuous strip spirally on a mandrel, and to pass the tube shell so produced together with the mandrel through an impregnating liquid, which on setting fills up the interstices formed in the shell by the spiral convolusions of the strip. All those processes however do not produce an insulating tube having a perfectly uniform texture or capable of resisting very high electric pressures. blow the process forming the subject of the present invention is essentially diiierent from known existing processes, and itcon sists submantially in making the tube of a web of paper having a width equal to the length of the tube to be madc,"and coiling the said web upon a mandrel under very great pressure and tension until the desired thickness of wall is obtained. Unsized paper of uniform texture is employed for this purpose.- The tube shell thus formed is placed into insulating composition and boiled therein so as to allow the insulating composition to penetrate gradually-the several thicknesses of paper constituting the coiled tube shell from the outside, and thus completely impregnate the tube shell. In

this manner a tube completely uniform throughout its thickness is produced because the paper web is coiled in uniform layers without any creases and the subse' quent impregnating operation in the heat causes the insulating composition to penetrate the layers of paper in a perfectly uniform manner from the outside to the inside. After the tubes have been thoroughly boiled Specification of Letters latent.

Patented in the insulating composition the mandrels lowed to' remain in the liquid insulating composition. The tubes then drip gradually from top to bottom whereby both the inside and outside of the tubes acquire an extremely smooth and uniform surface.

One way of carrying out the. improved process will'now be described by way of example with reference to the accompanying drawings 1n wlnch:-*-

May 7,1912.

are removed from the tubes which are al- Figure 1 is a vertical section of the machine for coiling the paper web; Fig. 2 is an end elevation of the machine; Fig. 3 is a vertical section of the vessel in which the tubes are impregnated, and an elevation of a vessel for continuing the insulating composition; Fig-.- 4 is a plan thereof, and Fig. 5 is a detail view of a device for fixing the mandrel and the tubes for the purpose of impregnating the latter.

'l'he-mandrel 1 on to which the paper web- 3 is coiled that is unwound from a roll 2. is mounted between two or more pressing rolls i. In the presentexample, three pressing rolls are provided.

In view of the small diameter and very great length of the'cylindrical mandrel 1, and also with the object of greater accessibility, and of exerting a greater pressure,

the pressing rolls -l are each preferably made of small diameter, and therefore counter-pressing rolls 5 are provided for the purpose of preventing bending of the pressing rolls. l Theupper rolls 4 and dare mounted at both ends in such a manner that they can be shifted upwardly for the purpose of insertion and removal of the mandrel 1, and. also of enabling the rolls to yield in the upward direction as the thickness of the paper shell increases on the'mandrel'l.

For the purpose of coiling the paper tube shell, the end of the paper web 3 is suitably fastened to the periphery of the mandrel 1, for instance by means of a thin streak of adhesive.

For coiling, only the mandrel 1 is driven counter-clockwise, while thenpressing rolls l to very great tension and pressure while it IS being coiled, so that the several layers are laid very tightly and closely upon one an 1 other.

With the object of increasing the tight-/ ness of the ceiling, and also of expelling as far as possible allthe moisture from the paper web, the latter is passed. over a cylinsired thickness by the coiling, a narrow strip 'stantially free spacesbetween them, which of adhesive is appliedto the paper for the conclusionof the-coiling, and the paper is cut across behind the said strip. The end of the paper in being coiled up then sticks to thee-oiled paper tube. The tube is thereby formed of non-adhering thicknesses orlayers and wlnch by reason ofthe molsture expellingprocess leave the pores opened, thoroughly dried, and quite independent of each other, 2'. e. the tube layers have subspaces receive the insulating solution. This I condition would not obtain ,where the sur-l face of the sheet is covered with an adhesive to unite the layers when thesheet is rolled into tube form. The coiled paper tube while on the mandrel is then placed. in the impregnating vessel for impregnating with the insulating composition.

For the purpose of impregn g, a large number of the paper tubes on their mandrels are placed iii-the imprgn'at'ingvessel 8 shown in Fig. 3. For this purpose the inandrels are 'set upright side by side with their lower journals 9 in a perforated plate 10. A similarly. perforated plate 11 is placed upon the upper endsof the mandrels. The perforations in the upper plate 11 are sufliciently large toall'ow-of the mandrels being .removed upwardly through them (Fig. 5).

For the purpose of keeping the tubes upright between the plates '10 and 11, during and after the removal of the mandrels, circular grooves 12 into which enter the ends of the tubes are provided in the plates around the perforations for the mandrels (F ig. 5). Preferably a similarly perforated plate 13 is also placed on the plate 11, and to this plate 13 the screw threaded upper'ends ofthe mandrels 1 are fixed by means of nuts 14. In order to remove themandrels from the impregnated tubes, it is therefore merely necessary to lift the plate 13 to which all the mandrels are attached by the nuts 14.

Since it would .be impossible to remove the mandrels fromthe impregnated or 'unimpregnated tubes that have been coiled upon them under great pressure and great tension," the following expedientis employed: w

I Before the coiling of-the paper web, all

the mandrels are coated with a thin layer For the purpose of impregnating, the

tubes with the man'drels are placed upright fastened down air-tight. Then,- while preferably heating the vessel 8 by means of its heating jacket 15, a vacuumis produced in it, whereby all the moisture and air is sucked out of the paper. .After. the vacuum has been maintained for a certain time,.byopening a valve-16, the heated and therefore liquefied impregnating composition is 'admitted from a vessel 17 into the vessel 8 preferably from below until thetubes are completely covered by it. I

In order to effect a thorough penetration of the paper layers of the tubes by the liquid impregnating composition, the composition is not only kept freely liquid permanently by heating the heating jacket 15, but also a high pressure is prpduced inside the vessel 8 whereby-the liquid composition is forced into the wall of the tubes.

The impregnatii'ig composition which must also have a high degree of insulation, may be composed of a mixture of beeswax, paraffin, earth wax, Japan wax, carnauba wax, and the like, and resins such as colophony, asphalt, pitch, and the like.

The mandrels 1 are removed from the tubes that are held between the two plates 10 and 11, while the tubes are still come pletelyimmersed in the impregnating composition. The im regnating composition is drawn off gradual y from the bottom of the' vessel only after the tubes have been taken out.

" As shown in Fig. 4, the vessel 8 is placed by means of the stop .valves 16 into communication with the two vessels 17 and 18 that contain the impregnating composition. After the heated liquid composition contained in the vessel -8 is .forced, out of the vessel 8 back into one or the other of the vessels 17, 18 by means of compressed air the valve 19'. The tubes are upright in the I vessel 8, and therefore as the composition is being forced out,.the excess composition on the tubes gradually runs down the tubes to the bottom, so that when the tubes have bein the vessel 8 and the cover of the latter is impregnating operation, the

supplied through come quite cold, their inner and outer surfaces will be very smooth and. appear as if polished.

The insulating tubes made accordin to this invention are rendered by their uni orm internal structure highly insulating as well as highly resistant to damp. Their walls of .pa er..

marines are comparatively resistant to mechanical influences and they are'air-tight. This involition, thusproduces an insulating tube of extremely good quality.- Any other unsiaed fibrous *inaterial may be employed instead If-it is desired that the insulating tube be capable of resisting piercing by sharp instruments such as nails or the like, then one or more layers of wire gauze or sheet metal 20 are rolled into the tube as it is being formed (see ,FigQl). Since the metal insertion is placed between the layers of paper said insertion. is prevented from rusting by reason of the insulating composition with which the tube-is treated.

What I claim is 1. A process for making insulating tubes consisting in drying a sheet of fabric to expel the moisturetherefromand open the pores of the same, rolling said sheet, under tension for its Whole Width on a mandre to form a tubular body of non-adhering thicknesses; placing said mandrel and tubular body in an impregnating solution to com pletely immerge the tube; and then withdrawing .said mandrel from the tube, sub stantially as described.

2. A process for making insulating tubes consisting in rolling a sheetof fabric on a mandrel to form a tube; placing said tube in a closed chamber; creating a vacuum in the chamber to remove moisture from the tube; and then admitting an insulating solu tion into said chamber to saturate the tube;

substantially as described.

Av process for making insulating tubes consisting in rolling a sheet of fabric on a mandrel to form a tube; placing the tube in closed chamber; creating a vacuum in the chamber to remove moisture from the tube;

and then expelling the solution from the chamber under pressure and allowing the solution to drain from the tubes, substantially as described.

A process for making insulating tubes.

consisting in drying a sheet of fabric to expel the moisture and open the pores thereof, rolling said sheet, under tension, for its whole \yidth on a mandrel, which is coated with an insulating medium, to form a tubular body of non-adhering thicknesses; placing said mandrel and tubular body in a closed chamber; creating a vacuum in the chamber to further remove moisture from the tube; then admitting an impregnating solution in the chamber to completely immerge the tube; and then admitting a fluid under pressure into said chamber to impregnate the tube with said solution, substantially as described.

In testimony whereof, I have atlixed my signature, in presence of two Witnesses.

VICTOR PINDTER v. PINDTERSHOFEN.

Witnesses:

ADA MARIE Buonn, ADELAIDE FUNK. 

